Can't install kali on usb

Hi guys, i'm trying to install kali on my usb, but every time something goes wrong. the bios didn't recognize the usb, or there are error on start. so i decided to try with version 1.1, but here, like in 2.0 there is nothing to do.
every time i download the iso
format my usb 8 GB
using unetbootin i create the live usb
restart and....nothing

Hope someone got the solution. actualy in my laptop i'm running ubuntu 14.04 and have only this partition.
Thanks all :o

you use wrong method to make boot usb and also you need to read post here on forum.
you have all answers in posts, just find it.

How are you installing it? Along side another OS or by it's self? If you're doing along with another OS, which one is it?